erp5_core_test: Add a test for sqlvar type="nb".

sqlvar type="nb" was broken by sqlvar patch without being noticed,
thus test is required. See commit ebdc34d4.
16 jobs for for_testrunner_1 in 0 seconds (queued for 1 second)
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Master

00:44:36

passed ERP5.PerformanceTest-Master

00:26:48

failed ERP5.UnitTest-Master

01:29:14

failed ERP5.UnitTest-Zope2

02:23:22

passed SlapOS.Eggs.UnitTest-Master.Python2

00:18:13

passed SlapOS.Eggs.UnitTest-Master.Python3

00:20:32

passed Wendelin.UnitTest-Master

00:37:12

failed ERP5.CodingStyleTest-Master

01:35:04

passed ERP5.PerformanceTest-Master

01:19:18

passed ERP5.UnitTest-Master

02:02:29

failed ERP5.UnitTest-Zope2

03:04:34

passed SlapOS.Eggs.UnitTest-Master.Python2

00:19:11

passed SlapOS.Eggs.UnitTest-Master.Python2

00:26:32

passed SlapOS.Eggs.UnitTest-Master.Python3

01:07:59

passed SlapOS.Eggs.UnitTest-Master.Python3

00:21:59

failed Wendelin.UnitTest-Master

01:30:54